Method of purifying carbohydrate solutions, etc.



Patented Feb.15,1927. 1,618,148

UNITED STATES PATENT OFFICE- No Drawing. Application filed February 21, 1923. Serial No. 620,490.

While the essential features of my invenof extended scientific research and experition are applicable to the electrical coagumental investigation of :the subject, I am enlation and precipitation of impurities in abled to attain the desired result by practicarbo-hydrate solutions generally, I herein cally a single operation, thereby saving time 5 by way of exemplification, consider and deand labor'in manipulation, simplifying the scribe them, mainly, as appertaining more apparatus involved, and reducing cost of particularly to the treatment of saccharine manufacture toan extent equivalent, 21p.- solutions for the purpose of eliminating, in proximately, of from five to ten per cent per a simple andinexpensive manner, the colorpound of product. Incidentally I thereby 10 ing matter, etc, contained therein, so as to also economize space and increase the capacrender the final sugar product pure and ity of a refining plant, considered in a uniwhite at a nominal cost as compared with tary sense, Which is likewise an important methods of sugar refining heretofore known factor'as related to cost of production. in theart. In a majority of cases the colloids con- 15 With this understanding, the distinctive tained in solutions of the character desigfeature of my invention consists in effecting nated, are of positive electric polarity, (alcoagulation and precipitation of deleterious though not necessarily sofor reasons herematter from solutions containing carbo-hyinafter stated) so that in exemplifying my drates, and especially from sugar held in soprocess it will be convenient to consider lution, by the introduction into the solution, treatment of the solution to be decolorized in suitable proportions, of colloids of oppoand purified by the introduction thereinto of site electrical polarity to effect the neutralcolloids of negative electric polarity, with ization of the colloids initially present in the understanding that I do not limit my the solution ;-an incidental feature in this invention in this respect. connection being the specific use of a colloi- Thus, for convenience of illustration, I

dal tannate of iron, an extremely active colwill indicate the preferred treatment of one loid for the purpose, all as hereinafter fully ton of raw sugar dissolved in water to a denset forth. I 4 sity of 80 Baum. To this slightly acid When a soluble tannate and a soluble iron solution three and one-half grams, or bout 30 salt (both crystalloids) are brought into one eighth of an ounce, of a colloidal tannate contact with each' other, a soluble active of iron may be added, together with about colloidal solution of tannate of iron is proone pound of diatomaceous earth, and the duced possessing a negative charge of elecwhole heated to about 160 F. As a consetricity. The iron and tannin are nowmlquence of this admixture-,the colloidal color- 35 croscopically divided into particles consisting matter and impurities of positive electric ing of atoms together with molecules and polarity contained in the solution will be ions forming what is called a micell whlch 'coagulated and precipitated by the electrois electrically charged. If this comes into negative colloidal character of a colloidal contact with a positive charged colloid such tannate of iron, so that by passing the heteras the yellow colored constituent of raw ogeneous resultant through a filter press or sugar or syrup, it causes it to coagulate and bag filter the insoluble precipitated coloring can now be removed by filtration, due to the matter and impurities held in suspension in 3 fact that the two charges of electricity (electhe syrup will be segregated therefrom, and tronic action) have become neutralized and on passing this through a char filter, gives a r are no longer in the colloidal state. water white liquid which yields a solution LIA Heretofore, in sugar refining particularly,- of pure white liquid, which on boiling in a the elimination of coloring matter and im-- vacuum pan, etc., gives perfectly refined, purities from the saccharine solution precrystalline sugar of the highest commercial paratory to crystallization has been a diffigrade and value. I cult and tedious problem, necessitating var Since raw sugars vary in color content, of rious preliminary steps and operations, and intense tinctorial power, and impurities, the rendering a pure white product comparaquantity of colloid of opposite electric po. tively and proportionately expensive. larity to be added to the soluticn must be in By my inventiomwhich is the outcome proportion to the initial collolds contained therein, as less or more than the requisite equivalent would prevent coagulative action. Hence, the importance of ascertaining the proper quantity of colloid of opposite elec- 5 tric polarity to be added to asaccharine solution to bethus treated, which may be accomplished in the following manner.

For instance, to ascertain the requisite amount of negative colloid to be added to 1 the aforesaid colloidaliy opposite solution of one ton. of sugar, the following means and formula may be utilized.

(A) Six glass tubes, four feet long by about 7 inch inside diameter and drawn 1 out to inch bore at one end, are supported in a stand and each partly filled with 100 grams uniform char of 20/40/60 mesh, and having a piece of cotton wool in bottom to hold the char in place. 20 (B) 700 grams raw sugar and 500 grams (l) 1.6 cc. (C) in 157 cc. (B) 32th lbs. per ton, or 14 parts per million. (Grams per ton).

(2) 0.8 cc. (C) in 157 cc. (B) 64th lbs. per

ton, or 7 parts per million. (Grams per ton).

(3) 0.4 cc. (C) in 157 cc. (B) 128th lbs. per ton, or 3.5 parts per million. (Grams per ton).

(4) 0.2 cc. (C) in 157 cc. (B) 256th lbs. per-ton, or 1.75 parts per million. (Grams per ton). .1 0

(5) 0.1 cc. (C) in 157 cc. (B) 500th lbs. per ton, or 0.88 parts per million. (Grams per ton). a

s 0.05 cc. (0) in 157 cc. (B) 1000th lbs. per ton, or 0.44 parts per million. (Grams per ton). With tannic acid at 100 cents per 1b., fer- 60 ric chloride 25 cents per 1b., and using 1000tl lb. colloid per ton, we have- Y 100 1000 0.100 cent 1 0.125 cent per ton to treat the sugar. Six portions of 157 cc. are treated with 1, 2, 3, 4, 5 and 6 amounts of the colloid, mixed and run into the char tubes. On complate drainage, the tube giving the lightest or white liquor, contains the proper amount of colloid per ton to be added.

I prefer to use iron-blue tannin, but the iron gxreen type, and also other metals,'as bismut manganese, as well as purely inorganic colloids, etc., may also be used. A colloidal tannate has no chemical or invertive action on the sugar.

If the solution to be purified contains either soluble iron or tannin, these should be converted first into an active colloidal tanwater together with 25 grams kieselguhr, is heated to 160 F. until all sugar is in solution, and then filtered clear.

100 cc. of this 30 Baum liquor contains 7 0 grams sugar.

157 cc. of this 30 Baum liquor contains 110 grams sugar.

(C) Into a glass stoppered 100 cc. graduated cylinder, run 10 cc. water followed by 1 cc. each of 5% tannic acid and 5% ferric chloride. Mix and immediately dilute to 100 cc.(C).

100 cc. (C) contain 2 cc. of 5% of negative colloid.

Y 100 cc. (C) contain 0.1 gram of negative colloid.

- 1.6 cc. (C) contain 0.0016 gram of negative colloid.

1.6 cc. (0) in 157 cc. (B) or 110 grams sugarequals lb. per ton sugar or 14 per million.

nate of iron by adding thereto a soluble tannate or iron salt respectively, before determining and adding the required amount of negative colloid to remove the colloid of op posite sign, namely the yellow colloid of raw sugar. This yellow colloid is partly produced by a mould growth.

W'ith this process of refining sugar, the present method of defecating with lime and phosphoric acid, which form dark colored, glucosates and result in lowering the purity of the sugar solutidn, is entirely done away with, simply' a treatment with this colloidal tannate of iron or negative colloid (mineral organic salt) and filtration immediately with or without kieselguhr, with. subsequent char treatment, is all that is required to produce white liquors.

Since some raw sugars are acid and others alkaline in reaction, the colloidal tannate of iron in acid liquors react as negative colloid. while the same colloidal tannate in alkaline liquors reverses its charge and becomes a positive colloid. In the alkaline state the colloidal tannate splits up, the iron forming a basic condition with basic action, and therefore possesses the positive colloidal property;

Examples (A) Fibres in alkaline solution are negative and precipitate the yellow color.

Fibres in acid solution are positive and will not precipitate the yellow color.

(B) Hydrated ferric oxid in colloidal state is positive in acid solution, while in alkaline solution, its charge or electric sign, is negative. 1

For the above reason the colloidal tannate of'iron is only an example of a colloid of opposite sign, I may use either negative or positive colloids according as the reaction of the liquors vary.

The yellow or other coloring matter being usually in combination with other impuri-,

ties in solution, such as bacteria, yeast,

, moulds, albumins, gums, pectin, polyphenols,

phenolcarboxylic acids, catechol, oxidases,

chlorophyll, wax, fat, essential oil's, resins and mineral salts (ash), on precipitation, also carry down these interfering bodies, and this is partly the cause of the resulting. pure white liquors above described. l V

What I claim as my invention and desire to secure by Letters Patent is 1 The method herein set forth of eliminatlng impurities from solutions containing carbo-hydrates consisting in the neutralization of the electro-positive colloids by the introduction into the solution of tannate of 'of iron as acolloidal sol, and then passing it through decolorizin char.

3. The method herem set forth of coagulating and precipitating im urities from solutions containing carbo-lliys rates, consisting in neutralizing the colloi initially present therein by the introduction into said solution, of tannate of iron as a colloidal sol,

substantially as and for the purpose specified."

y 4. The method herein set forth-of coagu lating and precipitating impurities held in a carbo-hydratesolution, consisting in neutralizing the colloids of a positlve polarity initially present thereiniby the introduction into said solution of tannate'of iron as a colloidal sol, substantially as and for the purpose specified. Y

5. The method herein set forth of coagulating, precipitating and eliminating 1mpurities held in a carbohydrate solution,

consisting in neutralizing the colloids of a positive polarity initially present therein, by the introduction into said solution of tannate of iron as a colloidal sol, and then'pa'ssing the same through decolorizing char, sub.-

stantially as and forthe purpose specified.

1 6. The method herein set forth, of coagulating, precipitating and eliminating 1m-,

purities held in negative solution, consisting into active colloidal sol of tannate of'iron by adding thereto a soluble iron salt thereafter which neutralizes the positive col'loid present, and then decolorizing char.

lating, precipitating and eliminating 1mpuritles held in a carbo-hydrate solution, consisting in converting iron already in solu:

ti'on into active negative colloidal sol ofta'nnate of iron by adding thereto a soluble tan-' in converting tannate already in solution a passing the same through co 7 The method herein set forth, of 'coagus nin salt which neutralizes the positive colloid present, and then passing'the same through, I

decolorizing char.

'8. The improvement in, purifying a hydrate solutionswhich comprises forming 1 within said solutions tannate of iron as a colloidal sol, and then passing th Same through decolorizing char. a v I v CHAR-LES, B. DAvIs 

